And so concerned are they about the effects on their boy that they are bringing him up to be 'gender neutral'.

This means that Lisa, 23, and her husband, Martin, 34, encourage Max to wear both boys' and girls' clothes, and to play with conventionally female – as well as male – toys.

Rather than worrying if he decides not to play football, and asks instead for someone to paint his fingernails with glittery polish, they instead see it as a form of cute self-expression.

Lisa said: "If Max wants to wear a pink tutu and fairy wings, then he can wear it.

"He's just expressing himself. I don't want to put him in a certain box and treat him that way. I want to teach him to be whatever he wants to be. He can pick his own clothes and, as long as they're warm enough for the winter, I'll get him whatever he wants."

A typical day will see Max, who turns two later this month, spend the morning playing with his collection of toy cars, planes, tractors, and dinosaurs.

Then after lunch he will swap his lumberjack shirt and jeans for a dark blue, knee-length dress decorated with pink flamingos before he takes his blonde-haired doll for a walk in her pram, before stopping to pretend to breastfeed her.

Lisa, from Walsall, West Midlands, said she gets the 'odd funny look' and 'a bit of hostility' but by and large people are 'supportive' of how she raises Max.

She said: "Once we explain how we are bringing our son up, and why, people tend to understand.

"I hope that Max won't get teased when he's older. But part of what we are trying to do with Max is to instil such a sense of confidence, and a sense of who he is, that he won't care what anyone else thinks."

Lisa, a stay-at-home-mum, took the decision to allow Max to identify as either a girl or a boy 12 months ago, after seeing high-profile rape cases being discussed on parenting websites.

She said: "Gender stereotypes can be so damaging. They teach little boys to be aggressive and dominant over women.

"There's research out there saying that the whole 'boys will be boys' thing basically teaches lads that it's OK to be a certain way, because it's in their nature to be aggressive. It's detrimental for them and for females."

The decision was fully supported by Martin, an unemployed courier.

She said: "I think my husband is more of a feminist than I am. His biggest concern about the whole thing is usually 'does Max have the right shoes to go with that dress!'"

Martin added: "My parents told me that I played with my sister's dolls as a child and it doesn't bother me. I can't see why it would bother anyone."

They are adamant that Max has thrived under the gender-neutral regime, pointing out that he is able to string three or four-word sentences together, and is 'almost' potty-trained.

In normal circumstances, Max would be required to start wearing gender-specific clothes when he starts at school.

However Lisa and Martin have a contingency plan that will allow him to continue dressing as he pleases.

"However, if he does eventually choose to go to school, and wants to wear a girl's uniform, I certainly won't stop him."

She added: "It doesn't matter if he's homosexual, bisexual, transsexual or asexual as far as I'm concerned. I didn't give birth to him to say 'I'm only going to love you if you're this way'. I love him for who he is."

The concept of gender-neutral parenting first became popular among feminists in America during the 1970s, when it inspired the actress Marlo Thomas to write a best-selling children's book called 'Free To Be... You and Me.'

Recently, it has experienced a small revival. In 2011, a Canadian couple made headlines after refusing to reveal the gender of their new-born child Storm in what they called 'a tribute to freedom and choice'.